Flight Mechanics Support to the Selection of Candidate Vehicles for Human Space Transportation and Experimental Atmospheric Entry
- Paper number
IAC-05-C1.8.01
- Author
Mr. Rodrigo Haya Ramos, DEIMOS Space S.L., Spain
- Coauthor
Mr. Juan-Carlos Bastante, DEIMOS Space, Spain
- Coauthor
Mr. Joao Araujo, DEIMOS Engenharia, Portugal
- Coauthor
Mr. Augusto Caramagno, DEIMOS Space, Spain
- Coauthor
Mr. Stefano Portigliotti, Alenia Spazio, Italy
- Coauthor
Mr. Massimilio Bottacini, Alcatel Alenia Space Italia, Italy
- Year
2005
- Abstract
This paper describes the methodology and application for the Flight Mechanics support on the Mission Analysis and GNC areas to the selection of an atmospheric entry vehicle candidate either for Human Space Transportation (HST) missions or for Experimental Atmospheric Entry. The potential candidate vehicles for those missions range from classical capsules (Soyuz, Apollo, Viking…), advanced capsules (Biconic shape without control surfaces) and high-performance lifting bodies (Colibri, Clipper, Sphynx, slender bodies…).
The design of an atmospheric entry vehicle is a complex task where many disciplines are involved since the initial steps due to the particularities of this type of vehicles: flight across many regimes (from hypersonic down to subsonic) with a limited mass budget and volumetric efficiency and high degree of automatic operations. Mission Analysis and GNC is one of the contributors to the Operational Requirements of the vehicle that closely interacts with the System Architecture Design before the performance assessment of the vehicle.
The aiming of the Mission Analysis and GNC support to the vehicle selection and design is to consider the greatest number of requirements that have an impact into the Flight performance of the vehicle using methods and tools as much as detailed as possible. This is an equilibrium between the detailed assessments for already selected options and the parametric trade-offs to not to constraint the design to a particular solution. For instance, the knowledge, even preliminary, of the aerodynamic characteristics of the shape introduces a key element in the selection of more detailed design methods and tools, whose conclusions ad recommendations will be more reliable.
One of the most important outputs of this support is the selection of the best shape and configuration candidate for a specific mission, either operational (HST) or demonstrator. The process is made up of the following steps:
Vehicle design: shape selection and configuration
The entry corridor is computed besides the performance maps and stability characteristics. The proposed approach considers all of those three arguments at the same time. Thus, the following criteria are considered:
- Path constraints during entry: maximum heat flux, maximum dynamic pressure, maximum load factor, passive to active transition oxidation for CSi ceramics and the Equilibrium Glide Boundary margin. These constraints define the classical entry corridor for entry vehicles.
- Stability margins: longitudinal static stability and lateral-directional dynamic stability introduces and additional corridor in terms of allowed angle of attack
- Trim performance derived from the Landing Site Network requirements (cross-range capability) and payload mass capacity expressed in terms of lift-to-drag ratio and Ballistic coefficient.
Vehicle design: nominal trajectory and entry interface window
The use of a trajectory optimizer based on the Gradient Restoration Algorithm allows the characterization of the entry vehicle capabilities inside the identified entry corridor and the computation of a precise Entry Interface Point (120 km height) window considering both exo-atmospheric and endo-atmospheric flight phases.
Vehicle performance: GNC assessment
A guidance algorithm based on the tracking of a free-shaped drag-energy reference profile is proposed as the appropriate trade-off algorithm for the evaluation of that guidance capability of the candidates through intensive Monte-Carlo simulations where state uncertainties, environment perturbations and system inaccuracies are evaluated.
Vehicle design: RCS allocation and sizing
As a part of the Design Consolidation Loop, actuators allocation and specification and fuel budgets is performed. It is the result of a detailed controllability assessment, control authority estimation and actuators allocation and sizing process derived from the previous vehicle guidance capability assessment. The successful application of this approach to currently on-going projects on Europe related with Human and Cargo Transportation to ISS and Atmospheric Reentry Experimental vehicles, shows that the iterative process inherent to the design of a aerospace vehicle is alleviated.
- Abstract document
- Manuscript document
IAC-05-C1.8.01.pdf (🔒 authorized access only).
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